This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The overall aim of this proposal is to examine the interacting impact of adrenal and ovarian aging on the central nervous system (CNS) of primates. Using rhesus macaques as a pragmatic animal model, we have begun to test the hypothesis that aging-related attenuation of dehydroepiandrosterone (DHEA) release exacerbates the perimenopausal decline in estradiol. We have evidence that this adrenal steroid can act as a precursor for estradiol synthesis in the CNS, and so it is likely to contribute to the maintenance of healthy brain function in the young, and its aging-related attenuation may exacerbate the neuropathologies that develop after menopause. We have trained animals to perform noninvasive cognitive tests and we are currently evaluating their performance after dietary supplementation with DHEA. The studies are also examining the impact of how adrenal steroids affect sleep-wake cycles, which can contribute to effective cognitive performance. By elucidating the interacting impact of declining ovarian and adrenal steroids on CNS function, we expect to lay a foundation for the development of therapies for many aging-associated disorders in women, such as cognition, learning, and attention, as well as perturbations of the circadian sleep-wake cycle.